Electric machine and method of operating the electric machine

ABSTRACT

A method of and apparatus for controlling an electric machine. The method can include using a controller to detect whether power is present at a first node of the controller, detect whether power is present at a second node of the controller, generate at least one signal based at least in part on the detection, and energize the electric machine using a detected power when the at least one signal indicates power is present at at least one of the first node, the second node, and a combination of the first node and the second node.

RELATED APPLICATIONS

This patent application claims the benefit of U.S. patent applicationSer. No. 10/662,052, filed on Sep. 12, 2003, and U.S. Patent ApplicationNo. 60/538,717, filed on Jan. 23, 2004, both of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The invention generally relates to electric machines (e.g., an inductionmotor), and more particularly to methods of and apparatus forcontrolling electric machines.

Many methods and apparatuses are used to control an induction motor.Exemplary methods and apparatuses include speed tap changing, triaccontrols, and fixed speed drive. In changing the speed taps, aneffective reduction in voltage or flux is provided to cause the motor torun at a reduced speed by the nature of a slip. The slip is ameasurement of how much the movement of the rotor follows the excitationfield, and is defined as the difference between the frequency of theexcitation energy and the speed of the motor. While these controlsprovide adequate speed control, they do so at the expense of efficiencyas the motor runs at a higher slip which is proportional to rotorconduction loss.

Electric machines (e.g., induction motors) are often utilized inheating, ventilation, and air conditioning (HVAC) systems to driveblowers that move fluid (e.g., air) through the system. Electricmachines are also used in other applications (e.g., to drive fluidpumps) that require adjustment of a control parameter of the electricmachine (e.g., speed, torque, fluid flow, and the like) to meet thesystem requirements.

SUMMARY OF THE INVENTION

Although numerous methods and apparatus are known to adjust a controlparameter of an electric machine (e.g., speed tap changing, triaccontrol, fixed speed drives, and the like), new methods and apparatusthat provide efficient operation of electric machines and that simplifyinstallation would be welcomed by those of skill in the art.

An electric machine assembly (e.g., an electric machine and a controllerconnected to the electric machine), or a portion thereof, incorporatingaspects of the invention can be used in new systems (e.g., HVAC systems)and/or retrofit in existing systems.

In a fixed speed drive, a series of signals are entered from thethermostat. These signals are then interpreted by a thermostat logic andtiming control that is enabled by an inverter circuitry and amicro-controller. While the fixed speed drive is an inexpensive andefficient product that provides half speed settings, a number ofcomponents will have to be replaced when an original equipmentmanufacturer (“OEM”) chooses to use the fixed speed drive. For example,the OEM may have to replace the induction motor with optional taps andrelays that are used to select voltage and speed. Replacing thesecomponents can be costly.

Accordingly, there is need for an interface between a thermostat and aninduction motor that also provides high motor efficiency at low-speed.In a first embodiment of the invention, a fixed speed drive (“FSD”)interface that includes a controller is configured to determine at whichspeed to operate a motor based on an AC input. The FSD interfacereceives electrical power from a tapped winding relay that has two ACinput connections: a high-speed connection and a low-speed connection.The high-speed connection directly drives the motor. The low-speedconnection powers the motor through an inverter or a capacitor andinverter sub-circuit. The FSD interface also includes ananalog-to-digital converter (“ADC”) that detects the difference involtage between the high-speed and low-speed voltages. Based on thisvoltage difference from the ADC, a controller determines whether topower the motor from the high-speed connection or from the low-speedconnection via the inverter.

The invention also provides a controller for an electric machine. Thecontroller includes a first voltage input, a second voltage input, andan inverter. The first voltage input is configured to receive a firstvoltage, and is operable to directly provide the first voltage to theelectric machine. The second voltage input similarly configured toreceive a second voltage. The inverter is coupled to the second voltageinput, and is activated by the second voltage. The inverter is alsoconfigured to frequency-regulate the second voltage to generate afrequency-regulated voltage, and to provide the frequency-regulatedvoltage to the electric machine.

The invention also provides a method of controlling an electric machine.The method includes the step of providing one source of unregulatedelectrical power selectively connected to the electric machine through arelay when a first speed is selected. The method includes the step ofgenerating a second source of regulated electrical power when a secondspeed is selected, the second source is selectively connected to theelectric machine through the relay. The method includes the step ofselectively switching the relay to connect the electric machine to theone source corresponding to the first speed, and to the second sourcefor operation of the electric machine corresponding to the second speed.

The invention also provides a method of controlling an electric machineusing a controller where the electric machine comprises a rotor and astator. The method can comprise detecting whether power is present at afirst node of the controller, detecting whether power is present at asecond node of the controller, and generating at least one signal basedat least in part on the detection. The method can also comprise using adetected power to energize the electric machine when the at least onesignal indicates power is present at at least one of the first node, thesecond node, and a combination of the first node and the second node.

The invention provides a method of controlling an electric machine usinga controller where the electric machine comprises a rotor and a statorand the controller comprises a programmable device. The method cancomprise detecting whether power is present at a first node of thecontroller, detecting whether power is present at a second node of thecontroller, generating at least one signal based at least in part on thedetection, and selecting a control mode of the programmable device froma plurality of control modes based at least in part on the at least onesignal. The method can also comprise the programmable device generatinga control signal based at least in part on the control mode and usingthe control signal to control energization of the electric machine wherethe electric machine is energized using a detected power.

The invention also provides a system comprising an electric machine anda controller. The electric machine can comprise a stator and a rotor andbe electrically connected to the controller. The controller can comprisea first node configured to receive a first power, a second nodeconfigured to receive a second power, and a first circuit configured todetect whether the first power is present at a first node of thecontroller, detect whether the second power is present at the secondnode, generate at least one signal, and isolate the at least one signalfrom the first power and the second power. The at least one signal canbe representative of whether the first power is present at the firstnode and whether the second power is present at the second node. Thecontroller can also comprise a second circuit configured to receive theat least one signal and generate a switch control signal, and a switchconfigured to selectively energize the electric machine based at leastin part on the switch control signal. The switch can use at least one ofthe first power, the second power, and a combination of the first powerand the second power to energize the electric machine when the at leastone signal indicates at least one of the first power is present at thefirst node, the second power is present at the second node, and acombination of the first power is present and the first node and thesecond power is present at the second node.

Other features and advantages of the invention will become apparent tothose skilled in the art upon review of the following detaileddescription, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a fixed speed drive interface.

FIG. 2 shows a circuit diagram of the interface shown in FIG. 1.

FIG. 3 illustrates a block diagram of a system including an electricmachine assembly.

FIG. 4 illustrates a solid-state detection circuit of the electricmachine assembly of FIG. 3.

FIG. 5 illustrates an electromechanical detection circuit of theelectric machine assembly of FIG. 3.

FIG. 6 illustrates a solid-state detection circuit of the electricmachine assembly of FIG. 3.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

DETAILED DESCRIPTION

FIG. 1 shows a block diagram of a FSD interface 100 coupled to aninduction motor 104. The interface 100 includes a thermostat relay ortapped winding relay 108 that receives a selection input from athermostat 112, and power from an alternating current (“AC”) powersource line-in 113. The interface 100 also receives a second AC powersource line-in at input 114. The tapped winding relay 108 has two speedoutputs 116, 120 representing a high-speed signal and a low-speedsignal, respectively. More specifically, the tapped winding relay 108will generate a high-speed signal when the motor 104 is run at afull-speed mode, whereas the tapped winding relay 108 will generate alow-speed signal when the motor 104 is run at a low-speed mode. Thelow-speed signal output 120 is fed into an electromagnetic interference(“EMI”) filter 124 to attenuate electromagnetic interference to generatea filtered low-speed output 126. The filtered low-speed output 126 andthe high-speed signal output 116 are coupled to a rectifying circuit 128to generate different levels of direct current (“DC”). The relay 108includes a plurality of inputs that are opto-isolated from the highvoltage side of the interface 100. The inputs can be configured forinputs, such as from a thermostat, to turn the interface 100 on for highspeed operation at an operating frequency, for example, between 50 Hzand 60 Hz, or to turn the interface on for a preset low speed operation.Furthermore, these inputs can also be configured for pulse widthmodulation control for running the motor 104 at low speed.

The high-speed output 116 and the low-speed output 120 are also summedindividually in a summing module 136 to provide different analogvoltages each representing a particular speed. For example, thehigh-speed output 116 can be summed into a 10KΩ resistor via a 1MΩresistor. Meanwhile, the filtered low-speed output 126 can be summedinto the 10KΩ resistor via a 499KΩ resistor to generate a summedvoltage. The summing module 136 thus provides a summed voltage thatrepresents either a high-speed signal or a low-speed signal. The summedvoltage is further conditioned at a filter module 148 to filter outundesirable noise or to clean the summed voltage so that the summedvoltage is detectable by an A/D converter (“ADC”) 140. The ADC 140 canbe embedded in a micro-controller 144 as shown in FIG. 1, or the ADC 140is external to the micro-controller 144. Examples of micro-controllerinclude embedded micro-controller, such as PIC 16C717I/SS fromMicroChip, and ST micro-controller from ST Microelectronics. Themicro-controller 144 reads in the summed voltage, and then generates asoftware control or selection signal based on the summed voltage. Themicro-controller 144 further includes an internal memory (not shown)that stores a plurality of codes and associated parameters. Although thememory is described as internal to the micro-controller 144, externalmemory can also be used in the interface to store data such ascustomer-specific parameters.

In the construction shown in FIG. 1, the rectifying circuit 128 includesa high-speed rectifier and a low-speed rectifier. Each of the rectifiersincludes a full wave bridge rectifier that has four diodes.Additionally, the high-speed rectifier and the low-speed rectifier sharea common pair of diodes, and a common rectified or DC output. The DCoutput is frequency regulated in a capacitor-inverter circuit or aninverter module 132. Particularly, the inverter module 132 includes afirst capacitor that is serially connected to a second capacitor. Theinverter module 132 also includes a plurality of power switches that arearranged in parallel with the first and the second capacitors. Theinverter module 132 is configured to provide one or perhaps only a fewfixed, predetermined speeds that are less than the rated full operatingspeed at full line voltage at input 116. At low speed, in order toreduce the torque output to match a fan law torque curve, themicro-controller 144 is configured to determine a quadraticvoltage-to-frequency control relationship between an applied voltage andthe operating frequency. As a result of the quadratic relationship, themotor 104 requires approximately only half the voltage normally suppliedduring full speed operation.

Although voltage-to-frequency control relationship described in theconstruction of FIG. 1 is quadratic, other forms of motor appliedvoltage/operating frequency relationship can also be used such that thevoltage and the frequency can be controllably applied. In theconstruction shown, the output frequency of the inverter module 132ranges from about 32 Hz to about 45 Hz based on inverter power limit. Apotentiometer can also be used to allow a user to adjust the outputfrequency in the same range.

Although the high-speed signal output 116 generally indicates the motor104 is to be run at full speed (for example, between 50 Hz and 60 Hz),it will be appreciated that multiple full speed scenarios can beinstalled in systems where a multiple-tapped motor is used.Specifically, in a construction where a single speed single phase(“SSSP”) permanent split capacitor (“PSC”) motor is used the high-speedsignal output 116 will have a single high-speed value at a fixedoperating frequency, such as 60 Hz. In yet another construction, theinterface 100 can be coupled to a multiple-tapped, single phase (“MTSP”)PSC motor. In such case, the high-speed signal output 116 will havemultiple speed values all running at a single operating frequency, suchas 60 Hz. Furthermore, the interface 100 will have multiple outputscoupled to the MTSP PSC motor.

Referring back to FIG. 1, the interface 100 also includes a switchingmodule 149. The switching module 149 selects either the low speed signalor voltage from the inverter module 132 based on a pair of softwaregenerated control or selection signals from the micro-controller 144.For example, when it is desired to run the motor 104 at high speed, thehigh speed output 116 of the tapped winding relay 108 will relay directAC power from input 113, while the low speed output 120 is essentiallyopen, deactivated or having a null value. The high-speed signal is alsosummed into the 10KΩ resistor via the 1MΩ resistor at the summing module136, filtered at the filtering module 148, and fed to the ADC 140.Thereafter, the micro-controller 144 processes the summed voltage andswitches the switching module 149 to relay the high-speed voltage to themotor 104. When it is desired to run the motor 104 at low speed, the lowspeed output 120 is EMI filtered, rectified at the rectifying circuit128, and frequency regulated at the inverter module 132. Efficient andfrequency regulated low speed voltage is thereafter provided to theswitching module 149. The frequency regulated low speed voltage can thenbe selected by the micro-controller 144.

A detailed circuit diagram 200 of the interface 100 is shown in FIG. 2.The low-speed output 120 is filtered at the EMI filter 124 to yield afiltered low-speed output 126. The filtered low-speed output 126 and anEMI filtered AC power line-in 115 are coupled to a low-speed rectifierof the rectifying circuit 128 to generate a low-speed DC signal. Thelow-speed rectifier includes a first pair of forward-biased diodes 150,154, and a second pair of reversed-based diodes 158, 162. Meanwhile, thehigh-speed signal output 116 together with the EMI filtered AC powerline-in 115 are coupled to a high-speed rectifier to generate ahigh-speed DC signal. Specifically, the high-speed rectifier includes apair of forward-biased diodes 154, 166, and a pair of reversed-biaseddiodes 158 and 170. In other words, both the low-speed rectifier and thehigh-speed rectifier share the diodes 154 and 158. A DC bus feedbackmonitor 182 couples the rectifying circuit 128 to the inverter module132. The DC bus feedback monitor 182 is configured to monitor therectified voltage (sometimes referred to as a DC bus voltage or a DCspeed signal) of the rectifying circuit 128. When the monitored DC speedsignal changes, the DC bus feedback monitor 182 will alert themicro-controller 144 to adjust the output duty cycle of the invertermodule 132 accordingly. The DC bus feedback monitor 182 is alsoconfigured to detect different types of full speed AC voltages, such as115 VAC and 230 VAC. The DC speed signal is then fed to the invertermodule 132 to provide one or perhaps only a few fixed, predeterminedspeeds that are less than the rated full operating speed at full linevoltage at input 116.

Furthermore, either the high-speed signal output 116 is summed into a10KΩ resistor via a 1MΩ resistor, or the filtered low-speed output 126is summed into the 10KΩ resistor via a 499KΩ resistor, to generate asummed voltage that represents an analog high-speed signal or low-speedsignal. The summed analog voltage is then filtered via aresistor-capacitor type filter before being fed into the ADC 140 of themicro-controller 144. In the construction shown, a 49KΩ resistor isarranged in parallel to a 1 μF capacitor. It should be noted that otherfilter combinations, and other resistors and capacitor values can alsobe used to clean up the undesirable noise in the analog summed voltage.

The switching module 149 (FIG. 1) includes two switches 174 and 178 toselect between a high-speed input voltage and a low-speed input voltage,as described earlier. Specifically, the micro-controller 144 sends apair of software control signals or soft control signals as selectionsignals to the switches 174 and 178 based on the summed voltage.Meanwhile, the inverter module 132 and the high-speed voltages frominputs 114 and 116 provide a low-speed voltage input and a high-speedvoltage input to the switches 174 and 178, respectively. When theselection signals from the micro-controller 144 represent high-speedsignals, the switches 174 and 178 will couple the high-speed voltagesfrom inputs 114 and 116 to the motor 104. At this time, the invertermodule 132 is disabled, while a small amount of power is supplied to themicro-controller 144. When the selection signals from themicro-controller 144 represent low-speed signals, the switches 174 and178 will couple the low-speed voltages from the inverter module 132 tothe motor 104.

Generally, power demanded by a load is typically a non-linear functionof the operating speed or frequency. Specifically, when P is the powerdemanded by a load, C is a constant and S is the motor speed, P=CS³.That is, reducing the motor speed or the operating frequency of themotor by half will reduce the power demanded by the load to ⅛ of theoriginal power when run at fill speed. That is, the interface 100 canefficiently deliver power to the motor 104 using the inverter module 132after a low-speed voltage has been detected. More specifically, when thelow-speed voltage has been detected, the inverter module 132 will beactivated. The inverter module 132, which includes a DC capacitor and aplurality of inverters, then regulates the low-speed voltage such thatthe low-speed voltage has a regulated or a pre-determined operatingfrequency. For example, when the input 116 is run at 60 Hz, the invertedoutput voltage from the inverter module 132 can be configured togenerate an operating frequency of 30 Hz, that is, half of the originalfrequency. Since the power is torque times speed, if the motor is run athalf speed and the power applied is ⅛ of its original value, the torqueis thus ¼ of its original value.

Furthermore, the interface 100 is also configured to detect feedbackfrom the motor 104 when the high-speed or low-speed voltage outputs 116,120 is disconnected via the tapped winding relay 108. This condition cancause both a high-speed and a low-speed voltage to be fed to theinterface 100. More specifically, when the tapped winding relay 108switches from high speed to low speed, there is normally a time delayfor the motor 104 to switch from high speed to low speed. Ideally, thereshould be no voltage at the high-speed output 116 when switching fromhigh speed to low speed. In practice, however, the motor 104 is stillspinning at high speed while the tapped winding relay 108 is switchingfrom high-speed voltage to low-speed voltage. At this time, the summingmodule 136 generates an unusually high summed voltage representing a sumof the high-speed voltage and the low-speed voltage. When both thelow-speed voltage and the high-speed voltage, or a unusually high summedvoltage, are detected by the ADC 140, the micro-controller is configuredto disconnect the switching module 149 from the motor 104, or to disablethe inverter module 132 such that no frequency-regulated voltage isgenerated. Thereafter, the micro-controller 144 is configured to readthe voltage output from the tapped winding relay 108, and to determinean appropriate soft control signal to generate to control the switchingmodule 149 as described earlier. In an alternative construction, themicro-controller 144 can also be configured to detect the presence ofthe condition where both voltages are fed to the FSD. Upon detectingthis condition, the micro-controller 144 can operate the motor 104 at athird speed, a low-speed, a high-speed, or a zero speed setting.

FIG. 3 illustrates an HVAC system 210 that includes an electric machineassembly 214. The electric machine assembly 214 includes an electricmachine 218 and a controller 222 connected to the electric machine 218.The illustrated electric machine 218 comprises an induction motor suchas a single-speed, single-phase (SSSP) permanent split capacitance (PSC)motor or a multiple-tapped, single-phase (MTSP) PSC motor. In otherconstructions, the electric machine 218 can comprise other types ofelectric motors (e.g., other types of induction motors, brushlesspermanent magnet motors, switched reluctance motors, direct currentmotors, and the like) and/or other types of electric machines having arotor and a stator. It should be understood that aspects of theinvention may be utilized in other types of systems and the HVAC system210 is merely shown and described as one such example.

With reference to FIG. 3, the controller 222 includes a first powerconnection 226 (e.g., a cooling mode power connection), a second powerconnection 231 (e.g., a heating mode power connection), and a thirdpower connection 234. A switch 238 (e.g., a thermostat relay) driven bya system control device 242 (e.g., a thermostat) selectively connects afirst power line 239 of a power source 246 (e.g., an alternating currentpower source such as a nominal 115 VAC, 230 VAC, 277 VAC utility powersource, a direct current power source, a combination of an alternatingcurrent power source and a direct current power source, and the like) tothe first and second power connections 226 and 231. The third powerconnection 234 can be connected directly to a second power line 240 ofthe power source 246.

The illustrated switch 238 connects the first power line 239 to thefirst power connection 226 when the system control device 242 generatesa high-speed control and connects the first power line 239 to the secondpower connection 231 when the system control device 242 generates alow-speed control. In other constructions, the system control device 242may generate controls corresponding to other control parameters of theelectric machine (e.g., torque, fluid flow, and the like). Fordiscussion purposes, the power received at the first power connection226 is described herein as a high-speed power HSP, the power received atthe second power connection 231 is described herein as a low-speed powerLSP, and the power received at the third power connection 234 isdescribed herein as a neutral or common power CP. It should beunderstood that the power received at each of the first and second powerconnections 226 and 231 can be utilized to adjust control parameters ofthe electric machine 218 other than speed.

With continued reference to FIG. 3, the controller 222 can also includea detection circuit 250, a control circuit 254, a switch 258, anexternal control signal connection 262, an isolation circuit 263, afilter circuit 264, a rectifier circuit 265, a feedback circuit 266, apower supply 267, and an inverter circuit 268.

The detection circuit 250 is configured to detect whether power ispresent at a first node of the controller 222 (e.g., the first powerconnection 226), detect whether power is present at a second node of thecontroller 222 (e.g., the second power connection 231), and generate adetection signal DS based at least in part on the detection. Althoughthe detection circuit 250 is illustrated as detecting whether power ispresent at the first power connection 226 and the second powerconnection 231, the detection circuit 250 can be configured to detectwhether power is present at any nodes of the controller 222. In someconstructions, the detection circuit 250 can detect whether power ispresent at more than two nodes of the controller 222.

The detected power can include an unregulated power (e.g., a utilitypower), a regulated power, and/or a combination of regulated power andunregulated power. The detected power can further include an alternatingcurrent, a direct current, and/or a combination of an alternatingcurrent and a direct current. As used herein, a detected power is apower that meets a predefined condition (e.g., a power sufficient toenergize the electric machine 218 for operation, a power that meets orexceeds a threshold level, and the like). Further as used herein, nopower generally refers to the lack of detected power (e.g., asubstantial absence of power, a power that does not meet the predefinedcoridition, and the like).

The detection circuit 250 can detect power by sensing at least oneelectrical characteristic representative of power (e.g., voltage,current, frequency, and the like). In the illustrated constructions, thedetection circuit 250 only determines whether a detected power ispresent at the respective node. In other constructions, the detectioncircuit can be configured to detect various levels of detected power atthe respective node.

The detection signal DS includes at least a first state, a second state,a third state, and a fourth state. The first state indicates detectedpower is not present at the first node and the second node. The secondstate indicates detected power is only present at the first node. Thethird state indicates detected power is only present at the second node.The fourth state indicates detected power is present at both of thefirst node and the second node. The detection signal DS can include oneor more signals. Accordingly, each signal of the detection signal DS canrepresent one or more states of the detection signal DS.

FIG. 4 illustrates a solid-state detection circuit 250 a. The detectioncircuit 250 a includes a first connection 270 configured to receive aninput representative of the high-speed power HSP, a second connection274 configured to receive an input representative of the common powerCP, and a third connection 278 configured to receive an inputrepresentative of the low-speed power LSP. As used herein and in theappended claims, terminology describing the use of a power or a signaland/or receipt of an input representative of a power or a signalincludes use and/or receipt of the actual power or signal and/or amodified version of the actual power or signal. The detection circuit250 a also includes a fourth connection 282 configured to provide afirst detection signal DS1 and a fifth connection 286 configured toprovide a second detection signal DS2. The detection circuit 250 a alsoincludes a first electrical isolation device 290 (e.g., an opticalisolation device) having a first portion connected between the first andsecond connections 270 and 274 and a second portion connected betweenthe fourth connection 282 and ground GND (e.g., a circuit groundprovided by the power supply 267). When a detected power is present atthe first connection 270 (e.g., when the voltage across the first andsecond connections 270 and 274 is greater than a threshold level), thefirst portion of the first device 290 acts as a signal transmitter(e.g., as a light source) and the second portion of the first device 290acts as a signal receiver (e.g., as a light detector). The firstdetection signal DS1 includes a logic low signal when the second portionof the first device 290 receives the transmitted signal and a logic highsignal the second portion of the first device 290 does not receive thetransmitted signal.

The detection circuit 250 a also includes a second electrical isolationdevice 294 having a first portion connected between the second and thirdconnections 274 and 278 and a second portion connected between the fifthconnection 286 and ground GND. The second device 294 operates similar tothe first device 290. Accordingly, when a detected power is present atthe third connection 278 (e.g., when the voltage across the second andthird connections 274 and 278 is greater than a threshold level), thesecond detection signal DS2 includes a logic low signal, and when adetected power is not present at the third connection 278, the seconddetection signal DS2 includes a logic high signal.

The detection signal DS that includes the first detection signal DS1 andthe second detection signal DS2 can be in the first state when detectedpower is not present at the first connection 270 and the thirdconnection 278, the second state when detected power is only present atthe first connection 270, the third state when detected power is onlypresent at the third connection 278, and the fourth state when detectedpower is present at both of the first connection 270 and the thirdconnection 278. The detection circuit 250 a may be configured togenerate an alternative detection signal DS in other constructions. Useof the first and second devices 290 and 294 in the detection circuit 250b results in electrical isolation of power present at the first, second,and/or third connections 270, 274, and 278 from the first and/or seconddetection signals DS1 and DS2. In one construction, the first and seconddevices 290 and 294 include a Toshiba TLP280 photocoupler. In otherconstructions, other types of electrical isolation devices can beutilized.

FIG. 5 illustrates an electromechanical detection circuit 250 b. Thedetection circuit 250 b includes a first connection 298 configured toreceive an input representative of the high-speed power HSP, a secondconnection 302 configured to receive an input representative of thecommon power CP, and a third connection 306 configured to receive aninput representative of the low-speed power LSP. The detection circuit250 b also includes a fourth connection 310 configured to provide afirst detection signal DS3 and a fifth connection 314 configured toprovide a second detection signal DS4. The detection circuit 250 b alsoincludes a first electrical isolation device 318 having a first portionconnected between the first and second connections 298 and 302 and asecond portion connected between the fourth connection 310 and groundGND. When a detected power is present at the first connection 298 (e.g.,when the voltage across the first and second connections 298 and 302 isgreater than a threshold level), the first portion of the first device318 acts as a signal transmitter (e.g., as an electromagnetic fieldgenerator) and the second portion of the first device 318 acts as asignal receiver (e.g., as a switch having a portion movable in responseto the electromagnetic field). The first detection signal DS3 includes alogic low signal when the second portion of the first device 318receives the transmitted signal and a logic high signal when the secondportion of the first device 318 does not receive the transmitted signal.

The detection circuit 250 b also includes a second electrical isolationdevice 322 having a first portion connected between the second and thirdconnections 302 and 306 and a second portion connected between the fifthconnection 314 and ground GND. The second device 322 operates similar tothe first device 318. Accordingly, when a detected power is present atthe third connection 306 (e.g., when the voltage across the second andthird connections 302 and 306 is greater than a threshold level), thesecond detection signal DS4 includes a logic low signal, and when adetected power is not present at the third connection 306, the seconddetection signal DS4 includes a logic high signal.

The detection signal DS that includes the first detection signal DS3 andthe second detection signal DS4 can be in the first state when detectedpower is not present at the first connection 298 and the thirdconnection 306, the second state when detected power is only present atthe first connection 298, the third state when detected power is onlypresent at the third connection 306, and the fourth state when detectedpower is present at both of the first connection 298 and the thirdconnection 306. The detection circuit 250 b may be configured togenerate an alternative detection signal DS in other constructions. Useof the first and second devices 318 and 322 in the detection circuit 250b results in electrical isolation of power present at the first, second,and/or third connections 298, 302, and 306 from the first and seconddetection signals DS3 and DS4. In one construction, the first and seconddevices 318 and 322 include a relay. In other constructions, other typesof electrical isolation devices can be utilized.

Each of the detection circuits 250 a and 250 b is configured to detectthe presence of power when the detected power includes a nominal voltagein a range between approximately 90 VAC and 277 VAC. In otherconstructions, the detection circuits 250 a and 250 b can be configuredto detect alternative ranges of power. The detectable power range of thedetection circuits 250 a and 250 b includes a lower thresholdcorresponding to a minimal line voltage of a nominal 115 VAC powersource and an upper threshold corresponding to a nominal 277 VAC powersource. Accordingly, the controller 222 can be utilized in systems thatreceive power from one of a plurality of different alternating currentpower sources. In some constructions, the lower threshold of the powerrange can be decreased and/or increased by adjusting under-voltagecircuitry of the controller 222, and the upper threshold of the powerrange can be decreased and/or increased by adjusting power ratings ofcircuitry of the controller 222.

FIG. 6 illustrates a solid-state detection circuit 250 c. The detectioncircuit 250 c includes a first connection 326 configured to receive aninput representative of the high-speed power HSP and a second connection330 configured to receive an input representative of the low-speed powerLSP. In some constructions, as illustrated in FIG. 6, the inputrepresentative of the low-speed power LSP can include an inputrepresentative of a filtered low-speed power FLSP where the filteredlow-speed power FLSP is generated using the filter circuit 264. Thedetection circuit 250 c also includes a third connection 334 configuredto provide a detection signal DS5. The detection circuit 250 c includesa resistive network having a first resistive device 338 (e.g., a 1meg-ohm resistor) connected between the first and third connections 326and 334, a second resistive device 342 (e.g., a 499 kilo-ohm resistor)connected between the second and third connections 330 and 334, and athird resistor 346 (e.g., a 10 kilo-ohm resistor) connected between thethird connection 334 and ground GND. In other constructions, theresistive network can be alternatively configured.

The resistive network sums the voltage associated with each detectedpower to generate the detection signal DS5. The detection signal DS5 canbe in the first state when detected power is not present at the firstconnection 326 and the second connection 330, the second state whendetected power is only present at the first connection 326, the thirdstate when detected power is only present at the second connection 330,and the fourth state when detected power is present at both of the firstconnection 326 and the third connection 330. The detection circuit 250 ccan be configured to generate an alternative detection signal DS inother constructions.

Referring back to FIG. 3, the control circuit 254 is configured toreceive the detection signal DS, select a control mode based at least inpart on the detection signal DS, and generate a switch control signalSCS based at least in part on the selected control mode. In theillustrated construction, the control circuit 254 includes aprogrammable device (e.g., a micro-controller such as a PIC 16C717I/SSmicro-controller from MicroChip, a ST micro-controller from STMicroelectronics, and the like). In other constructions, the controlcircuit 254 can include logic-based components or other circuitryconfigured to generate the switch control signal SCS based at least inpart on the selected control mode. The control circuit 254 can includean associated memory internal and/or external to the control circuit 254that stores a plurality of codes and associated parameters.

In some constructions, the detection signal DS is filtered to enhancethe signal for detection by the control circuit 254. As illustrated inFIG. 6, the third connection 334 is electrically connected to a filter350 to filer the detection signal DS5. The filter 350 includes a diodethat half-wave rectifies the detection signal DS5, a resistor-capacitorarrangement to reduce undesirable noise in the detection signal DS5, anda zener diode to establish a maximum voltage level of the detectionsignal DS5. Filters may be alternatively configured in otherconstructions.

In some constructions, an analog-to-digital converter (ADC) 358 (FIG. 3)is utilized to convert inputs representative of a detection signal DSfrom an analog signal to a digital signal. The ADC 358 can be embeddedin the control circuit 254 as shown in FIG. 3, or the ADC 358 can beexternal to the control circuit 254.

The control circuit 254 can include a plurality of control modesincluding an OFF control mode, a first operational control mode, secondoperational control mode, and a third operational control mode. Thethird operational control mode can include an external control mode asdescribed further below. In the illustrated construction, the OFFcontrol mode is selected when the detection signal DS is in the firststate, the first operational control mode is selected when the detectionsignal DS is in the second state, the third operational control mode isselected when the detection signal DS is in the third state, and thefourth operational control mode is selected when the detection signal DSis in the fourth state. In other constructions, the control modes cancorrespond to other states of the received detection signal DS.

The switch control signal SCS can include one or more signals. In theillustrated construction, the switch control signal SCS includes atleast one signal for each switch the switch 258 includes. The switch 258can include a plurality of switches (e.g., relays) configured toenergize the electric machine 218 for operation using a power inputreceived by the switch 258 (e.g., a power input representative of thehigh-speed power HSP, a power input representative of an inverted powerIP generated by the inverter circuit 268 using the low-speed power LSP,and the like). In some constructions, the switch 258 can includemultiple switches for a single power input (e.g., the switch 258 caninclude multiple relays to handle the current associated with a largepower input such as those utilized to energize a one horsepower electricmachine for operation).

FIG. 3 illustrates one example of how power inputs of the switch 258 canbe generated. The low-speed power LSP and the common power are fed toand filtered by the filter circuit 264. The filter circuit 264 caninclude an electromagnetic interference (EMI) filter that attenuateselectromagnetic interference present in the low-speed power LSP and/orthe common power CP. The filter circuit 264 generates a filteredlow-speed power FLSP and a filtered common power FCP which are fed alongwith the high-speed power HSP to the rectifying circuit 265.

The illustrated rectifier circuit 265 includes a high-speed rectifierand a low-speed rectifier. The filtered low-speed power FLSP and thefiltered common power FCP are fed to the low-speed rectifier to generatea low-speed direct current signal, and the high-speed power HSP and thefiltered common power FCP are fed to the high-speed rectifier togenerate a high-speed direct current signal. Each of the high-speed andlow-speed rectifiers includes a full-wave rectifier having four diodesconnected in a bridge arrangement. As illustrated in FIG. 6, thehigh-speed rectifier and the low-speed rectifier can share a common pairof diodes, and a common direct current signal DC (i.e., the low-speeddirect current signal and the high-speed direct current signal areequal).

The direct current signal DC is frequency regulated in the invertercircuit 268. The illustrated inverter circuit 268 includes acapacitor-inverter circuit (e.g., a first capacitor serially connectedto a second capacitor) and a plurality of power switches that arearranged in parallel with the first and the second capacitors. Theinverter circuit 268 can be configured to provide one or more inputpowers to the switch 258. Each input power can correspond to apredetermined control parameter (e.g., speed, torque, fluid flow, andthe like) of the electric machine 218.

The feedback circuit 266 can include a direct current feedback monitorthat couples the rectifying circuit 265 to the inverter circuit 268. Thefeedback circuit 266 can be configured to monitor the direct currentsignal DC (sometimes referred to as a direct current bus voltage or adirect current speed signal) of the rectifying circuit 265. When themonitored direct current signal DC changes, the feedback circuit 266alerts the control circuit 254 to adjust the duty cycle of the invertercircuit 268 accordingly. The feedback circuit 266 can also be configuredto detect the value of the high-speed power HSP. Such information can beutilized by the control circuit 254 to adjust the switch control signalSCS (e.g., to stop energization of the electric motor 218 if thehigh-speed power HSP is outside an acceptable range of input power forthe electric machine 218).

The illustrated power supply 267 includes a DC-DC power supplyconfigured to provide a supply power to the control circuit. In someconstructions, the power supply 267 can provide power to othercomponents of the controller 222.

The external control signal connection 262 of the controller receives aninput representative of an external control signal ECS. Similar to othersignals discussed herein, the external control signal ECS can includeone or more signals. Depending on the system configuration, the externalcontrol signal ECS can be provided directly to the external controlsignal connection 262 via the system control device 242 or indirectly tothe external control signal connection 262 via the system control device242. In one construction, the external control signal is received andinterpreted by a system control board (e.g., a furnace board thatincludes the switch 238). The system control board uses the interpretedresults to control switches (e.g., the switch 238). The external controlsignal ECS can include signals representative of the outputs of thecontrolled switches on the system control board. In an HVAC system forexample, the external control signal ECS can include a high cool signal,a low cool signal, a high heat signal, a low heat signal, a fan onlysignal, and auxiliary heat signal, and the like. Often, the externalcontrol signal ECS includes one or more nominal 24 VAC signals. Theisolation circuit 263 isolates the control circuit from the externalcontrol signal ECS. In one construction, the isolation circuit 263includes at least one optical isolation device. In other constructions,the isolation circuit includes at least one relay.

Depending on the type of system in which the electric machine assembly214 or a portion thereof is installed, the installer may which to causethe control circuit 254 to select a specific mode (e.g., the externalcontrol mode). In the illustrated construction, the external controlmode is selected when detected power is present at both the first andsecond node. Accordingly, in the illustrated construction, the installercan ensure the control circuit 254 enters the external control mode byelectrically connecting the first and second power connections 226 and231 to the first power line 239. This may be accomplished by connectingone of the first and second power connections 226 and 231 to the firstpower line 239 and connecting a jumper between the first and secondpower connections 226 and 231. The switch control signal SCS is based atleast in part on the external control signal ECS when the controlcircuit 254 enters the external control mode. In some constructions, theswitch 238 can be eliminated from the system control board when a systemis designed for hard-wired connection of the first and second powerconnections 226 and 231 to the first power line 239.

Various features and advantages of the invention are set forth in thefollowing claims.

1. A method of controlling an electric machine using a controller, theelectric machine comprising a rotor and a stator, the method comprising:detecting whether power is present at a first node of the controller;detecting whether power is present at a second node of the controller;generating at least one signal based at least in part on the detectingacts; and using a detected power to energize the electric machine whenthe at least one signal indicates power is present at at least one ofthe first node, the second node, and a combination of the first node andthe second node.
 2. A method according to claim 1 wherein the controllercomprises an inverter, and wherein using a detected power to energizethe electric machine comprises providing a detected power to theinverter, the inverter generating an inverted power using the detectedpower, and using the inverted power to energize the electric machine. 3.A method according to claim 1 wherein the detected power comprises atleast one of an unregulated power, a regulated power, and a combinationof an unregulated power and a regulated power.
 4. A method according toclaim 1 wherein the detected power comprises at least one of analternating current, a direct current, and a combination of analternating current and a direct current.
 5. A method according to claim1 wherein detecting whether power is present comprises detecting whetherpower is present that comprises a nominal voltage in a range betweenapproximately 90 volts alternating current and 277 volts alternatingcurrent.
 6. A method according to claim 1 wherein detecting whetherpower is present comprises detecting whether at least one of a voltage,a current, a frequency, and a combination of a voltage, a current, and afrequency is present.
 7. A method according to claim 1 wherein thecontroller comprises a solid-state circuit that performs the detectingacts and the generating act.
 8. A method according to claim 7 andfurther comprising electrically isolating the detected power from the atleast one signal, wherein the solid-state circuit also performs theelectrically isolating act.
 9. A method according to claim 1 and furthercomprising electrically isolating a detected power from the at least onesignal, wherein the controller comprises an electromechanical circuitthat performs the detecting acts, the generating act, and theelectrically isolating act.
 10. A method according to claim 1 andfurther comprising the controller receiving at least one externalcontrol signal, wherein using a detected power to energize the electricmachine is based at least in part on the external control signal whenthe at least one signal indicates power is present at both of the firstnode and the second node.
 11. A method according to claim 1 whereingenerating at least one signal comprises: generating a first signalbased at least in part on the act of detecting whether power is presentat a first node of the controller, and generating a second signal basedat least in part on the act of detecting whether power is present at asecond node of the controller.
 12. A method according to claim 1 whereinthe at least one signal comprises a first state, a second state, a thirdstate, and a fourth state, wherein the first state indicates a detectedpower is not present at the first node and the second node, wherein thesecond state indicates a detected power is only present at the firstnode, wherein the third state indicates a detected power is only presentat the second node, and wherein the fourth state indicates a detectedpower is present at both of the first node and the second node.
 13. Amethod of controlling an electric machine using a controller, theelectric machine comprising a rotor and a stator, the controllercomprising a programmable device, the method comprising: detectingwhether power is present at a first node of the controller; detectingwhether power is present at a second node of the controller; generatingat least one signal based at least in part on the detecting acts;selecting a control mode of the programmable device based at least inpart on the at least one signal, the control mode being one of aplurality of control modes of the programmable device; the programmabledevice generating a control signal based at least in part on the controlmode; and controlling energization of the electric machine using thecontrol signal, the electric machine being energized using a detectedpower.
 14. A method according to claim 13 wherein controllingenergization of the electric machine comprises controlling a controlparameter of the electric machine, and wherein the control parametercomprises at least one of speed, torque, fluid flow, and a combinationof speed, torque, and fluid flow.
 15. A method according to claim 13 andfurther comprising the controller receiving at least one externalcontrol signal, wherein the plurality of control modes comprises anexternal control mode, wherein selecting a control mode comprisesselecting the external control mode when the at least one signalindicates a detected power is present at both the first node and thesecond node, and wherein controlling energization of the electricmachine is based at least in part on the at least one external controlsignal when the external control mode is selected.
 16. A methodaccording to claim 13 wherein the plurality of control modes comprisesan OFF control mode, wherein selecting a control mode comprisesselecting the OFF control mode when the at least one signal indicates adetected power is not present at the first node and the second node, andwherein controlling energization of the electric machine comprises notenergizing the electric machine when the OFF control mode is selected.17. A method according to claim 13 wherein the plurality of controlmodes comprises a first operational control mode, wherein selecting acontrol mode comprises selecting the first operational control mode whenthe at least one signal indicates a detected power is present at thefirst and second nodes in a first defined manner, and whereincontrolling energization of the electric machine comprises energizingthe electric machine for high-speed operation when the first operationalcontrol mode is selected.
 18. A method according to claim 17 wherein theplurality of control modes comprises a second operational control mode,wherein selecting a control mode comprises selecting the secondoperational control mode when the at least one signal indicates adetected power is present at the first and second nodes in a seconddefined manner, and wherein controlling energization of the electricmachine comprises energizing the electric machine for low-speedoperation when the second operational control mode is selected.
 19. Amethod according to claim 18 wherein the plurality of control modescomprises a third operational control mode, wherein selecting a controlmode comprises selecting the third operational control mode when the atleast one signal indicates a detected power is present at the first andsecond nodes in a third defined manner, and wherein controllingenergization of the electric machine comprises energizing the electricmachine for one of a plurality of operations when the third operationalcontrol mode is selected, the plurality of operations comprising alow-speed operation and a high-speed operation.
 20. A method accordingto claim 19 wherein the first defined manner is a detected power beingpresent at only the first node, wherein the second defined manner is adetected power being present at only the second node, and wherein thethird defined manner is a detected power being present at both the firstnode and the second node.
 21. A method according to claim 13 whereindetecting whether power is present at a first node of the controllercomprises detecting a first detected power, wherein detecting whetherpower is present at a second node of the controller comprises detectinga second detected power, and wherein the first detected power and thesecond detected power are substantially equal.
 22. A system comprising:an electric machine comprising a stator and a rotor; and a controllerelectrically connected to the electric machine, the controllercomprising: a first node configured to receive a first power; a secondnode configured to receive a second power; a first circuit configured todetect whether the first power is present at a first node of thecontroller, detect whether the second power is present at the secondnode, and generate at least one signal, the at least one signal beingrepresentative of whether the first power is present at the first nodeand whether the second power is present at the second node, a secondcircuit configured to receive the at least one signal and generate aswitch control signal, and a switch configured to selectively energizethe electric machine based at least in part on the switch controlsignal, the switch using at least one of the first power, the secondpower, and a combination of the first power and the second power toenergize the electric machine when the at least one signal indicates atleast one of the first power is present at the first node, the secondpower is present at the second node, and a combination of the firstpower is present and the first node and the second power is present atthe second node.
 23. A system according to claim 22 wherein the firstcircuit detects the presence of the first power when the first powercomprises a nominal voltage in a range between approximately 90 voltsalternating current and 277 volts alternating current, and wherein thefirst circuit detects the presence of the second power when the secondpower comprises a nominal voltage in a range between approximately 90volts alternating current and 277 volts alternating current.
 24. Asystem according to claim 22 wherein the first circuit comprises asolid-state optical isolation device that electrically isolates at leastone of the first power, the second power, and a combination of the firstpower and the second power from the at least one signal.
 25. A systemaccording to claim 22 wherein the first circuit comprises anelectromechanical relay that electrically isolates the first power, thesecond power, and a combination of the first power and the second powerfrom the at least one signal.
 26. A system according to claim 22 andfurther comprising a system control device configured to provide atleast one external control signal to the controller, wherein thecontroller comprises a third circuit configured to electrically isolatethe at least one external control signal from the second circuit.
 27. Asystem according to claim 26 wherein the system control device comprisesa thermostat, and wherein the at least one external control signalcomprises a heat command signal and a cool command signal.
 28. A systemaccording to claim 22 and further comprising a system control boardconfigured to provide at least one external control signal to thecontroller, wherein the controller comprises a third circuit configuredto electrically isolate the at least one external control signal fromthe second circuit.
 29. A system according to claim 26 wherein theswitch control signal is based at least in part on the external controlsignal when the first power is present at the first node and the secondpower is present at the second node.
 30. A system according to claim 22wherein the second circuit comprises a programmable device having aplurality of control modes, wherein the plurality of control modescomprises an OFF control mode, a first operational control mode, asecond operational control mode, and a third operational control mode,wherein one of the plurality of control modes is selected based at leastin part on the at least one signal, and wherein the switch controlsignal is based at least in part on the selected control mode.
 31. Asystem according to claim 30 wherein the third operational control modecomprises an external control mode, wherein the external control mode isselected when the at least one signal indicates the first power ispresent at the first node and the second power is present at the secondnode.
 32. A system according to claim 30 wherein the switch does notenergize the electric machine when the OFF control mode is selected. 33.A system according to claim 30 wherein the switch energizes the electricmachine for high control parameter operation when the first operationalcontrol modes is selected, wherein the switch energizes the electricmachine for low control parameter operation when the second operationalcontrol mode is selected, and wherein the control parameter includes atleast one of speed, torque, fluid flow, and a combination of speed,torque, and fluid flow.